Radon 222 half-life: 3.82 days
emissions: alpha particle
health implications: Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer.
methods available: EPA tentative method 913.0.
chemical and physical properties: Little relationship between levels of 222Rn and 226 Ra. Granite aquifers have the highest radon concentrations. Radon is chemically inert and is not transported great distances from its source.
Polonium 218
half-life: 3.05 minutes
emissions: alpha particle
health implications: Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer.
methods available:
chemical and physical properties: The immediate progeny of 222Rn establish secular equilibrium in about four hours and all have short half-lives. They probably all decay locally before they have a chance to be deposited in a target organ. None of these progeny would be picked up in the gross alpha analysis because the radon is driven off in the procedure and the samples are held for three days before counting, thus all of the unsupported progeny will have decayed away.
Lead 214
half-life: 26.8 minutes
emissions: beta particle
health implications: Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer.
methods available:
chemical and physical properties: The immediate progeny of 222Rn establish secular equilibrium in about four hours and all have short half-lives. They probably all decay locally before they have a chance to be deposited in a target organ. None of these progeny would be picked up in the gross alpha analysis because the radon is driven off in the procedure and the samples are held for three days before counting, thus all of the unsupported progeny will have decayed away.
Bismuth 214
half-life: 19.7 minutes
emissions: beta particle
health implications: Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer.
methods available:
chemical and physical properties: The immediate progeny of 222Rn establish secular equilibrium in about four hours and all have short half-lives. They probably all decay locally before they have a chance to be deposited in a target organ. None of these progeny would be picked up in the gross alpha analysis because the radon is driven off in the procedure and the samples are held for three days before counting, thus all of the unsupported progeny will have decayed away.
Polonium 214
half-life: 1.6 x 10-4 seconds
emissions: alpha particle
health implications: Lung cancer and stomach cancer from ingestion. All of the short-lived (supported) progeny may be of concern. Equilibrium is established rapidly and in the distribution system where removal by adsorption is not as fast as in the aquifer.
methods available:
chemical and physical properties: The immediate progeny of 222Rn establish secular equilibrium in about four hours and all have short half-lives. They probably all decay locally before they have a chance to be deposited in a target organ. None of these progeny would be picked up in the gross alpha analysis because the radon is driven off in the procedure and the samples are held for three days before counting, thus all of the unsupported progeny will have decayed away.
Lead 210
half-life: 22 years
emissions: beta particle
health implications: Accumulates in the bone, its short-lived progeny, 210Bi then decays in place. It's a beta emitter, thus reducing its dose.
methods available: EML/HASL method Pb-01.
chemical and physical properties: Large concentrations of Rn in water could lead to detectable levels of 210Pb. Lead 210 may become regulated in the future.
Bismuth 210
half-life: 5.0 days
emissions: beta particle
health implications: 210Pb accumulate in the bone, its short-lived progeny, 210Bi then decays in place. It's a beta emitter, thus reducing its dose.
methods available:
chemical and physical properties:
Polonium 210
half-life: 138.4 days
emissions: alpha particle
health implications: The long half-life of this isotope makes it a possible concern, distributed in soft tissues as well as the bones.
methods available: EML/HASL method Po-01 and Po-02
chemical and physical properties: Large concentrations of 222Rn could lead to detectable levels of 210Po. In systems that have elevated 210Po, 222Rn is also elevated. In situations where 222Rn is elevated and there is no 210Po, it is believed to be due to adsorption of both the 210Pb and 210Po. Elevated 210Po is associated with significant sulfide concentrations and pH's around 6. Polonium 210 may become regulated in the future.
TH-232 SERIES
Thorium 232
half-life: 1.39 x 1010 years
emissions: alpha particle
health implications: The long half-life of this isotope makes it a possible concern, although due to alpha recoil the activity of 230Th is probably higher.
methods available: EPA tentative method 907.0.
chemical and physical properties: Extremely insoluble. Higher natural abundance than uranium, thus in the absence of secondary enrichment of uranium, 228Ra (progeny of 232Th) can be higher than 226Ra. Thorium may be more soluble in the presence of high concentrations of organic material. Carbonate aquifers, Baslatic aquifers, and quartise/sandstone aquifers have low thorium concentrations.
Radium 228
half-life: 5.75 years
emissions: beta particle
health implications: Two to three times more radiotoxic than 226Ra.
methods available: EPA method 904.0
chemical and physical properties: Radium does not form any soluble complexes. Since the percent abundance of thorium is higher than that of uranium, 228Ra can be greater than 226Ra
Actinium 228
half-life: 6.13 hours
emissions: beta particle
health implications:
methods available: Radium 228 is determined by measuring 228Ac and then back calculating to 228Ra. Reaches secular equilibrium in six hours.
chemical and physical properties:
Thorium 228
half-life: 1.9 years
emissions: alpha particle
health implications:
methods available: EPA tentative method 907.0.
chemical and physical properties: Extremely insoluble. Higher natural abundance than uranium, thus in the absence of secondary enrichment of uranium, 228Ra (progeny of 232Th) can be higher than 226Ra. Thorium may be more soluble in the presence of high concentrations of organic material. Carbonate aquifers, Baslatic aquifers, and quartise/sandstone aquifers have low thorium concentrations. May end up in solution via alpha recoil.
Radium 224
half-life: 3.64 days
emissions: alpha particle
health implications: Radiotoxicity is believed to be small because of the short half of 224Ra and progeny.
methods available: EPA method 903.0. Measures all alpha emitting radium isotopes. New Jersey method is specific for 224Ra.
chemical and physical properties: Activity is often equal to two times greater than 228Ra. Since the parent is thorium the 224Ra activity is usually unsupported, 224Ra/228Ra ratios greater than one are probably due to alpha recoil. This isotope may become regulated in the future. Should look at systems with high 228Ra. If 224Ra is present in the water supply the alpha activity may vary depending on when the sample is analyzed.>
Radon 220
half-life: 54.5 seconds
emissions: alpha particle
health implications: Decays through a series of short lived alpha emitting progeny, so it would have similar health consequences as 222Rn if it were present.
methods available: Can be mathematically calculated by doing the New Jersey method for 224Ra.
chemical and physical properties: Radon is chemically inert and is not transported great distances from its source.
Polonium 216
half-life: 0.158 seconds
emissions: alpha particle
health implications:
methods available: Can be mathematically calculated by doing the New Jersey method for 224Ra.
chemical and physical properties:
Lead 212
half-life: 10.6 hours
emissions: beta particle
health implications:
methods available: Can be mathematically calculated by doing the New Jersey method for 224Ra.
chemical and physical properties:
Bismuth 212
half-life: 60.5 minutes
emissions: beta particle
health implications:
methods available: Can be mathematically calculated by doing the New Jersey method for 224Ra.
chemical and physical properties:
Polonium 212
half-life: 3.1 x 10-7 seconds
emissions: alpha particle
health implications:
methods available:
chemical and physical properties:
Uranium 235 SERIES
Uranium 235 (percent abundance = 0.72%)
half-life 7.13 x 108 years
emissions: alpha particle
health implications: Bone and kidney, chemical toxicity probably more important due to its low specific activity. Radiotoxicity of 238U about the same as 234U.
methods available: EPA method 908.0 for total Uranium. Also EPA method 908.1, fluorometric.
chemical and physical properties: Soluble complexes are formed under oxidizing conditions especially when carbonates are present. Secondary enrichment can occur when reducing conditions cause the uranium to precipitate out. This leads to elevated 226Ra. 238U, 234Th, 234U, and 230Th usually behave as a group.
Thorium 231
half-life 25.6 hours
emissions: beta particle
health implications:
methods available:
chemical and physical properties: Extremely insoluble.
Protactinium 231
half-life 3.43 x 104 years
emissions: alpha particle
health implications:
methods available:
chemical and physical properties:
Actinium 227
half-life 22.0 years
emissions: beta particle
health implications:
methods available:
chemical and physical properties:
Thorium 227
half-life 18.6 days
emissions: alpha particle
health implications:
methods available:
chemical and physical properties:
Radium 223
half-life 11.1 days
emissions: alpha particle
health implications: Radiotoxicity is believed to be small because of the short half of 223Ra and progeny
methods available: EPA method 903.0. Measures all alpha emitting radium isotopes.
chemical and physical properties:
Radon 219
half-life 3.92 seconds
emissions: alpha particle
health implications:
methods available:
chemical and physical properties:
Polonium 215
half-life 1.83 x 10-3 seconds
emissions: alpha particle
health implications:
methods available:
chemical and physical properties:
Lead 211
half-life 36.1 minutes
emissions: beta particle
health implications:
methods available:
chemical and physical properties:
Bismuth 211
half-life 2.16 minutes
emissions: alpha particle
health implications:
methods available:
chemical and physical properties:
Thallium 207
half-life 4.79 minutes
emissions: beta particle
health implications:
methods available:
chemical and physical properties:
Neptunium
SERIES activities from series members are insignificant due to the extremely low concentrations of 237Np found in nature.
